Rotary electric switch with an automatic mechanism which resets it when no voltage is applied thereto

Abstract

The switch includes an electromagnet (9) with a moving core (10) which is retracted when voltage is applied. A configuration of three levers (11, 12, 13) which are fixed together in pairs when the switch is cocked. The first lever (11) is integral with the rotary control shaft (3). The second lever (12) pivots on a stationary middle shaft (23) due to the respective actions of the core being released and of an antagonistic spring (15). The third lever (13) pivots on the end shaft (28), is provided with a return spring (16) and holds the control shaft (3) and the first lever (11) in position by being fixed to the other two levers. The third lever which has a middle lock projection (29) for the first lever also has a transversal passage (24) with a notch (27) in which the free end (25) of the second lever (12) can move, said free end itself having a hooked portion (26) which co-operates with the notch (27) in the tripped position and allowing manual or automatic return to the rest position.

We claim: 
     
       1. A rotary electric switch with an automatic mechanism for resetting the switch to a rest position when insufficient voltage is applied thereto, said switch including, for said purpose, a rotatable control shaft fitted with a return spring for rotatably returning it to the rest position, an electromagnet with a moving core which, when released on a drop in voltage, triggers the return, and a configuration of three levers fixed together in pairs when said switch is cocked, said three levers comprising; a first lever integral with the control shaft, a second lever pivoting on a stationary middle shaft under the control of the respective actions of the core when released and of an antagonistic spring, a third lever pivoting on a stationary end shaft and fitted with a return spring to firstly hold the control shaft and the first lever in the operating position by fixing it to the other levers and secondly to release the first lever and cause the return of the switch to the rest position when said third lever is released by the second lever which is itself actuated by the core being released, the improvement wherein, in said switch, the shafts of the first and second levers are disposed on the same side of the third lever, said third lever having at its middle a lock projection for the first lever and a free end having a notched transversal passage in which the furthest end of the second lever from the core can move, said furthest end having a hooked portion located on the other side and opposite end to said second lever relative to the core so as to fix the end of the second lever in the notch of the notched passage when the core is retracted due to the effect of an electric voltage being applied to the electromagnet and the control shaft is placed in the cocked position. 
     
     
       2. An electric switch according to claim 1, wherein the notch of the transversal passage bears against the bearing surface of the hooked portion at an obtuse angle which promotes detaching and wherein the return spring of the control shaft combines with the return spring of the second lever to produce a return force which prevents detaching when the core is not released from the core. 
     
     
       3. An electric switch according to claim 2, wherein the force of the control shaft return spring is greater than that of the spring of the third lever so that the first lever releases itself from the lock projection of the third lever due to the effect of the return spring of the control shaft in the case where the hooked portion is released due to the action of releasing the core. 
     
     
       4. An electric switch according to claim 2, wherein the controlled rotation of the control shaft against the pull of the return spring when the core is retracted causes the notch in the transversal passage to slide on the bearing surface of the hooked portion and the third lever to rise and allow the first lever to pass beyond the lock projection of the third lever, then the hooked part of the second lever to be attached again to the notch in the transversal passage and the cocking of the switch under safety conditions identical to those of a switch including an extra contact for applying voltage to an electromagnet. 
     
     
       5. An electric switch according to claim 1, wherein the third lever has a lock notch located between the lock projection in the middle of the third lever and the end on which the third lever pivots.